Eluxadoline is a mixed μ-opioid receptor agonist δ-opioid receptor antagonist that has been developed for treatment of diarrhea-predominant irritable bowel syndrome. Compound of formula II is an intermediate in a process of synthesis of Eluxadoline, as described in U.S. Pat. No. 7,741,356.

The compound with formula (II) when prepared according to the process disclosed in U.S. Pat. No. 7,741,356 requires purification by column chromatography, which reduces overall yield. Moreover, the process is not amenable to large scale synthesis.
The present invention provides a process that overcomes these drawbacks. Thus, the invention relates to a novel method of preparing compound of formula (II), that results in a compound of high purity and yield. The invention also relates to a novel intermediate in the synthesis of compound of formula (II).